Portable containers for transporting liquid fuel such as gasoline provide a convenient way of replenishing expended fuels in devices that require periodic fueling (e.g., lawnmowers, vehicles, generators, etc.). Portable liquid fuel containers (e.g., gas cans) are commonly made of plastic and include a removable nozzle that connects to a fill opening of the container. The gas can is usually tipped to pour the fuel out of the nozzle. An air inlet is sometimes provided along the top side of the gas can to equalize pressure within the gas can for improved outflow of fuel through the nozzle.
Controlling the flow rate and the amount of fuel dispensed from the gas can be difficult, and is highly dependent on the tilt angle of the gas can, the amount of fuel contained in the gas can, a size of the nozzle opening, and the rate of air flow into the gas can during dispensing. As a result of these many variables, the vehicle or equipment being filled by the gas may be overfilled. Once fluid flow is set in motion, excess fluid readily collects and moves through the nozzle. Consequently, a rapid movement of the gas can to a non-dispensing position to stop the fluid flow sometimes fails to correct an overfill. Fluid overflows are hazardous, wasteful and may damage the environment and equipment upon which the fluid spills.